[REBASE & FF] [feature/supv] Fix Ring 3 stack indexing, sizing, and user mapping - #1768
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enter_runtime received the APIC ID and forwarded it to bsp_request_loop as a CPU index. On platforms whose APIC IDs are not 0..N-1 (e.g. 16, 18, 24, ...) this selected a Ring 3 stack outside the array the MM IPL provisioned, so the demoted routine faulted on its first push. Take the dense index the C core hands to entry_point and use it for the request path, keeping the APIC ID for the CpuManager APIs keyed by it.
… CPU count SyscallInterface::init was given the MAX_CPUS const generic capacity instead of the number of CPUs the MM IPL provisioned Ring 3 stacks for, so get_cpl3_stack happily returned stack pointers past the end of that array (supervisor memory) for any index between the real count and MAX_CPUS. Parse the MP Information HOB before the PassDown HOB and pass its CPU count in, so out-of-range indices are rejected.
The supervisor relied on the MM IPL to leave the per-CPU CPL3 stacks user-accessible; where that does not hold, the first push made by a demoted routine takes a page fault on a supervisor-owned page. Map the provisioned range read/write, non-executable and user-accessible during BSP init, after checking it lies inside MMRAM so nothing outside MMRAM is exposed to Ring 3, and verify every page afterwards so a misconfiguration fails at init rather than at the first demotion.
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Description
enter_runtimereceived the APIC ID and forwarded it to
bsp_request_loopas a CPU index.On platforms whose APIC IDs are not
0..N-1(observed: 0, 2, 4 … 46, BSP =16) this selected a Ring 3 stack outside the array the MM IPL provisioned, so
the demoted routine faulted writing to a supervisor-owned page. The dense
index the C core hands to
entry_pointis now used for the request path,while the APIC ID is still used for the
CpuManagerAPIs keyed by it.SyscallInterface::initwas given theMAX_CPUSconst generic capacity (32)rather than the number of CPUs the IPL provisioned stacks for (16), so
get_cpl3_stackreturned pointers past the end of that array, intosupervisor memory, for any index in between. The MP Information HOB is now
parsed before the PassDown HOB and its count is passed in, so out of range
indices are rejected with
InvalidCpuIndex.relied on the MM IPL to leave the per-CPU CPL3 stacks user-accessible. The
provisioned range is now mapped read/write, non-executable and
user-accessible during BSP init, after confirming it lies inside MMRAM so
nothing outside MMRAM is exposed to Ring 3, and every page is verified
afterwards so a misconfiguration fails at init instead of at the first
demotion.
How This Was Tested
Integration Instructions
N/A